Adjustable thermostat



Jan. 2, 1962 L. J. SIRI 3,015,235

ADJUSTABLE THERMOSTAT Filed April 8, 1959 INVENTOR. Lou/s J', Slkl.

3,015,235 ADJUSTABLE THERMOSTAT Louis .I. Siri, South Bend, Inth, assignor to Penn Controls, Inc., Goshen, Ind., a corporation Filed Apr. 8, 1959, Ser. No."804,971 4 Claims- (Cl... 73-4611) I This invention relates generally to thermally responsive devices and in particular to a device of this general type utilizing the difference in thermal expansion of dis similar metals.

In control applications it is common place to provide a thermally responsive element in the form of a laminated strip formed of two metal components having rather widely different thermal coeflicients of expansion. When the strip is mounted in cantilever fashion, an increase in ambient temperature will cause the free end of the strip to deflect linearly with temperature increase within a predetermined temperature range. The work performed by the bimetal element and available for operation of a switching mechanism, valve or other control means is the product of the force and deflection of the 'bimetal element.

The present invention provides an arrangement wherein the difference in thermal expansion of dissimilar metals is used to provide a deflection for operating a control means, the dissimilar metal elements being variable or adjustable in spacing to thereby vary the relative magnitude of the force and deflection or motion components of the work or energy output of the device.

The full nature of the invention will be understood from the accompanying drawings and the following description and claims:

FIG. 1 is a side view of a structure embodying the present invention.

FIG. 2 is a fragmentary side view illustrating one condition of adjustment of the device and a resolution of the forces generated upon a predetermined change in temperature.

FIG. 3 is a view similar to FIG. 2, but illustrating a further condition of adjustment of the device and a corresponding resolution of the forces generated upon a predetermined change in temperature.

Referring initially to FIG. l,'there is shown a temperature responsive device comprising a fixed elongated blade or element and a second, similarly shaped element or blade 11. The elements are disposed in overlying relation and rigidly joined at one end by any suitable means, such as a rivet 12, which serves to anchor the composite structure in cantilever fashion upon a support 13. The opposite ends of the'elements 10 and 11 are rigidly joined to each other and provided with means for operating a control structure which, as shown in FIG. 1, takes the form of a movable contact 14. A stationary contact 16, cooperating with the movable contacts, is rigidly mounted adjacent thereto. The element 10 is formed of any suitable material, but preferably of a metal having a relatively high thermal coeflicient of expansion. The element 11 is formed of a material having a relatively low thermal ooeflicient of expansion, such as Invar metal.

A means for adjusting the'spacing between the intermediate portions of the elements 10 and 11 is provided by an adjusting screw 17 which is threaded through the element 10 and at its lower end braced against the adjacent surface of the element 11. It will be understood that various other means might be provided for adjustably varying the spacing between the elements including variously sized fixed dimension spacers which might be ins'erted .between the inner surfaces of the two elements.

In operation, as will be apparent from FIG. 2, when the elements ,are spaced relatively closely together, a

United States Patent-Ofifice Patented Jan. 2, 1962 predetermined change in temperature of the elements will produce a force indicated at R. This resultant force has a relatively small vertical component indicated at 18 in FIG. 2. Since the work or energy output of the device for a predetermined change in temperature remains a constant, it will be evident that this available work is composed of a relatively large transverse deflection component and a relatively small force compo nent indicated at 18. As will be evident from FIG. 3, when the elements 10 and 11 are provided with a wider spacing, the available work output of the device, while it remains constant, is composed of 'a relatively small transverse deflection component and a relatively large force component, indicated at 18'. The adjustment of the spacing of the element thus provides a'rneans for varying the characteristics of the output of the device and permits it to be adapted to various control requirements. It will be understood that while the switch contacts 14 and 16 are herein disclosed as being operated by the elements 10 and 11, the device mightly similarly operate other control components, such as a pilot valve or the like.

While the invention has been disclosed and described in some detail in the drawings and foregoing description, they are to be considered as illustrative and not restrictive in character, as modifications may readily suggest themselves to persons skilled in this art and within the broad scope of the invention, reference being had to the appended claims.

The invention claimed is:

1. A temperature responsive device comprising a first elongated element having a relatively high thermal co efficient of expansion, a second elongated element having a lower thermal coeflicient of expansion, said elements being disposed in overlying relation having each end of said first element rigidly joined to the correspondingly positioned end of said second element, one end of the composite structure thereby formed being supported in cantilever fashion and the other end being adapted for operationof an electrical switching means, and an adjusting screw threaded through said first element intermediate the end of the element and bearing against said second edement, whereby said elements may be adjustably spaced to vary the relative magnitude of the force and deflection components of the energy output of said device resulting from a predetermined change in temperature of said elements.

2. A temperature responsive device comprising a first elongated element having a relatively high thermal coeflicient of expansion, a second elongated element having a lower thermal coeflicient of expansion, said elements being disposed in overlying relation having each end of .said first element rigidly joined to the correspondingly positioned end of said second element, one end of the composite structure thereby formed being supported in cantilever fashion and the other end being adapted for operation of a control means, and an adjustable abutment disposed intermediate the ends of said elements and extending therebetween, whereby said elements may be adj-ustably spaced to vary the relative magnitude of the force and deflection components of the energy output of said device resulting from a predetermined change in temperature of said elements.

3. A temperature responsive device comprising a first elongated element and a second elongated element having differing coeflicients of expansion, said elements being disposed in overlying relation having each end of said first element rigidly joined to the correspondingly positioned end of said second element, one end of the composite structure thereby formed being rigidly supported and the other end being adapted for operation of a 4. A temperature responsive device comprising a first elongated element and a second elongated element having differing coeflicients of expansion, said elements being disposed in overlying relation having one end of said first element and the correspondingly positioned end of said second element rigidly secured by a first single fastener to each other and to a supporting member and having the other end of said first element rigidly secured to the other end of said second element by a second single fastener which is adapted for operation of a con trol means, and an adjusting screw threaded through said I first element intermediate-the ends of said first element and bearing against said second element, whereby said elements may be adjustablyspaced to vary the relative,

magnitude of the force and deflection components of the output of said device resulting from a predetermined change in temperature of said elements.

References Cited in the file of this patent UNITED STATES PATENTS 304,695 Brinckerhoff Sept. 9, 1884 2,220,368 Heidbrink Nov. 5, 1940 2,332,518 Koci Oct. 26, 1943 2,338,474 Wilson Jan. 4, 1944 2,579,389 Mertler Dec. 18, 1951 FOREIGN PATENTS 899 Great Britain. Jan. 11, 1913 

